Device, method, and computer program product for creating print data and computer program product manufacturing method

ABSTRACT

This specification discloses a computer program product manufacturing method. This method is provided with a forming step, a combining step, and a storing step. The forming step instructs the printer to form a dot at a predetermined coordinate. The combining step creates a combination of the predetermined coordinate and a sub-coordinate which is different from the predetermined coordinate. A distance between the predetermined coordinate and a position of a dot formed when the printer tries to form the dot at the sub-coordinate is shorter than the distance between the predetermined coordinate and the position of the dot formed in the forming step. A storing step stores a computer program into a memory medium. The computer program includes instructions for ordering the computer device to perform a choosing step and a converting step. The choosing step chooses a coordinate from bit-mapped data. The converting step converts the coordinate chosen in the choosing step into the sub-coordinate in a case where the coordinate chosen in the choosing step has been combined with the sub-coordinate in the combining step.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No.2004-341928, filed on Nov. 26, 2004, the contents of which are herebyincorporated by reference into the present application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for creating print datautilized by a printer. The present invention further relates to a methodfor creating print data and a computer program product for creatingprint data. Further, the present invention relates to a computer programproduct manufacturing method. The printer of the present specificationincludes all devices for printing words or images onto a print medium.For example, the printer of the present specification includes ink jetprinters and laser printers. Ink jet printers and laser printers includecopying machines, fax machines, multifunctional products, etc.

2. Description of the Related Art

A printer utilizes colorant such as ink, toner, etc. to form points on aprint medium. Desired words or images are thus formed on the printmedium. In the present specification, a point formed on a print mediumby a printer utilizing colorant is termed a dot. For example, in thecase of an ink jet printer, a point formed on a print medium bydischarging a droplet of ink from a nozzle toward the print medium istermed a dot. Furthermore, a point formed on a print medium bydischarging a plurality of ink droplets onto the same location on theprint medium from one or a plurality of nozzles is also termed a dot.

An ink jet printer discharges ink droplets from nozzles towards a printmedium, thus forming dots on the print medium. The ink jet printer maybe utilized while connected with an external device such as a personalcomputer, or the like. In the case where an image shown on a display ofthe personal computer is to be printed by the ink jet printer, thepersonal computer creates bit-mapped data. The created bit-mapped dataincludes color information of each coordinate. In the case of a colorimage, the color information of the bit-mapped data is represented as acombination of color and color density of that color. Consequently,bit-mapped data of the color image includes a plurality of combinationsof coordinate, color, and color density. Further, in the case of amonochrome image, the color information of the bit-mapped data can berepresented as a combination of single color and color density, or canbe represented only as color density. The bit-mapped data of themonochrome image includes a plurality of combinations of coordinate,single color, and color density (or a plurality of combinations ofcoordinate and color density).

The personal computer chooses coordinates at which dots will be formedfrom the bit-mapped data. This process is performed based on the colorinformation of the coordinates included in the bit-mapped data. Thecoordinates are chosen from the bit-mapped data using, for example, thehalftone process or the dither method. The personal computer outputs theinformation representing the chosen coordinates to the ink jet printer.Here, this information is termed print data. The print data for colorprinting can be formed from, for example, combinations of a chosencoordinate and color (for example, any one out of cyan, magenta, yellow,and black). The ink jet printer receives the print data output from thepersonal computer, and forms dots based on the print data that has beenreceived. For example, in the case where a combination of the coordinate(x, y) and yellow is included in the print data, the ink jet printerforms a yellow dot at the coordinate (x, y).

FIG. 18 is a figure schematically showing an example of dots 100 formedby the ink jet printer. In the example shown in FIG. 18, the dots 100are formed in 8 rows×8 lines. The dots have not been filled with ink inFIG. 18. The numbers shown above the dots 100 are row numbers, and thenumbers shown to the left of the dots 100 are line numbers. Two dots 100that adjoin in the row direction or line direction overlap. The arrow Ain the figure shows the direction of movement of the print medium withrespect to the nozzles. Below, eight dots aligned in the A directionwill be termed a dot row, and eight dots aligned in a directionorthogonal to the A direction will be termed a dot line. In thisexample, eight dot rows and eight dot lines are formed. Below, the rowswill be represented as x coordinates and the lines will be representedas y coordinates. Sixty four coordinates (1, 1), (1, 2), etc. areincluded in the print data being utilized to form the dots 100 shown inthis example.

Ink is discharged from the nozzles while the print medium is moving withrespect to the nozzles in the direction of the arrow A. For example, theeight dots of the first dot row are formed by continuously dischargingink droplets from one nozzle while the print medium is moving withrespect to the nozzle in the direction of the arrow A. Similarly, theeight dots of the second dot row are also formed by continuouslydischarging ink from one different nozzle. Eight nozzles that are offsetin an X direction are required to form the eight dot rows shown in FIG.18. All the dots 100 are formed uniformly in the example shown in FIG.18, and printing could be termed satisfactory.

However, the timing at which ink is discharged from a certain nozzle maybe earlier or later than the intended timing. In this case, the dot rowformed by this nozzle is formed at a position that is displaced withrespect to the dot rows formed by the other nozzles. FIG. 19 shows anexample of the dots 100 where the dot rows were formed by eight nozzlesthat include a nozzle discharging ink at a timing later than theintended timing. In this example, the nozzle for forming the fifth dotrow discharges ink at a timing later than the intended timing. As aresult, the fifth dot row is displaced upwards. Here, satisfactoryprinting results cannot be achieved.

BRIEF SUMMARY OF THE INVENTION

The present invention presents a technique whereby satisfactory printingresults can be achieved. An example of the present invention will bedescribed using FIG. 20. FIG. 20 is a figure for allowing an overview ofthe present invention to be described. A method of manufacturing acomputer program product is taught in the present specification. Thiscomputer program product is utilized by a computer device to createprint data utilized by a printer. In this method, a forming step ofinstructing the printer to form a dot at a predetermined coordinate isexecuted. In the example shown in FIG. 20, the printer is instructed toform a dot at a predetermined coordinate E1. In this example, a dot isformed at a coordinate E2.

Next, in the case where a distance between the predetermined coordinateE1 and the coordinate E2 is more than a predetermined distance, acombining step is executed to create a combination of the predeterminedcoordinate E1 and a sub-coordinate. The predetermined distance may bechosen to be any value greater than zero. The coordinate adopted as asub-coordinate has the following relationship: a distance between thepredetermined coordinate E1 and the position of a dot formed when theprinter tries to form the dot at the sub-coordinate is shorter than thedistance F1 between the predetermined coordinate E1 and the position E2of the dot formed in the forming step. In the example shown in FIG. 20,a dot is formed at a coordinate E4 when the printer tried to form a dotat a sub-coordinate E3. A distance F2 between E1 and E4 is shorter thanthe distance F1 between E1 and E2. Consequently, the above relationshipis fulfilled by adopting the sub-coordinate E3. In this step, acombination of the coordinate E1 and the sub-coordinate E3 is created.

In the present method, a storing step of storing a computer program intoa memory medium is executed. The computer program includes instructionsfor ordering the computer device to perform a choosing step and aconverting step. In the choosing step, a coordinate is chosen frombit-mapped data. The bit-mapped data includes a plurality ofcombinations of a coordinate and color information. A combination of thecolor and color density may be included in the color information.Alternatively, only color density may be included in the colorinformation. In the choosing step, a coordinate is chosen based on thecolor information combined with the coordinate. In the choosing step,one coordinate may be chosen based on the color information of aplurality of coordinates. Alternatively, it may be determined whether tochoose the coordinate based only on the color information of onecoordinate. In the case where the coordinate chosen in the choosing stepis E1 of FIG. 20, the coordinate E1 chosen in the choosing step isconverted into the sub-coordinate E3 in the converting step.

In the case of the above example, the print data includes theinformation that the dot should be formed at the sub-coordinate E3. Theprinter tries to form the dot at the sub-coordinate E3 and, in thiscase, the dot is formed at the coordinate E4.

FIG. 20 and the contents based thereon that have been described aboveare an example, and the scope of the present invention is not restrictedbased on FIG. 20 or the above contents. For example, the scope of thepresent invention is not restricted by the directions X, Y, and A inFIG. 20. The scope of the present invention is determined on the basisof the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic diagram of an ink jet printer and a personalcomputer.

FIG. 2 shows a simplified view of nozzles and piezoelectric elements ofthe ink jet printer.

FIG. 3 shows a schematic view of the configuration of an electricalcircuit of the ink jet printer and the personal computer.

FIG. 4 shows functions realized by the personal computer.

FIG. 5 shows a flowchart of a method of manufacturing a computer programproduct.

FIG. 6 (a) shows dots formed along a base line. FIG. 6 (b) shows dotsthat have been formed in positions displaced from the base line.

FIG. 7 shows contents of a first table.

FIG. 8 shows a flowchart of a data process.

FIG. 9 shows a flowchart of a print data creating process.

FIG. 10 shows a flowchart of the print data creating process.

FIG. 11 shows contents stored in a two value data memory.

FIG. 12 shows contents stored in a buffer memory.

FIG. 13 (a) shows one coordinate. FIG. 13 (b) shows eightsub-coordinates obtained from the coordinate shown in FIG. 13 (a).

FIG. 14 shows the contents of a second table.

FIG. 15 shows how the contents stored in the buffer memory change. FIG.15 (a) shows the contents stored when one line data of a line M has beenwritten. FIG. 15 (b) shows the contents stored when the stored contentsof a lower storage region of FIG. 15 (a) are shifted to an upper storageregion. FIG. 15 (c) shows the contents stored when one line data of lineM+1 has been written into the stored contents of FIG. 15 (b). FIG. 15(d) shows the contents stored when the stored contents of the lowerstorage region of FIG. 15 (c) are shifted to the upper storage region.FIG. 15 (e) shows the contents stored when one line data of line M+2 hasbeen written into the stored contents of FIG. 15 (d). FIG. 15 (f) showsthe contents stored when the stored contents of the lower storage regionof FIG. 15 (e) are shifted to the upper storage region.

FIG. 16 shows contents stored in a print data memory.

FIG. 17 (a) shows dots formed when the representative embodiment has notbeen adopted. FIG. 17 (b) shows dots formed when the representativeembodiment has been adopted.

FIG. 18 shows an example of dots.

FIG. 19 shows an example of dots formed in the case where one dot rowhas been displaced.

FIG. 20 is a figure for allowing an overview of the present invention tobe described.

DETAILED DESCRIPTION OF THE INVENTION

The computer program product can be utilized for creating print datautilized by an ink jet printer. The ink jet printer comprises aplurality of nozzles for discharging ink toward a print medium and atransferring device for transferring the nozzles and/or the print mediumalong a Y direction in a state in which at least one nozzle faces theprint medium. Each nozzle is offset along a X direction which isperpendicular to the Y direction. Further, the ink jet printer may beeither a line type or a serial type.

As shown in FIG. 20, it is preferred that a predetermined coordinate E1and a sub-coordinate E3 are aligned in a Y direction (an A direction).In this case, it is preferred that if a dot E2 is formed further alongin the Y direction (upwards) relative to the intended coordinate E1, thesub-coordinate E3 is formed further along in the opposite side in the Ydirection (downwards) relative to the coordinate E1. Further, it ispreferred that if a dot is formed further along in the opposite side(downwards) in the Y direction from the coordinate E1, a sub-coordinateis formed further along in the Y direction (upwards) relative to theintended coordinate E1.

A combination of the predetermined coordinate and an adjustment amountcan be created in a combining step. For example, a combination of thepredetermined coordinate (x, y) and the adjustment amount (a, β) can becreated in the combining step. In this case, the coordinate (x, y) maybe converted in a converting step into a sub-coordinate (x+a, y+β) byadding the adjustment amount (a, β) to the coordinate (x, y). Creatingthe combination of the predetermined coordinate and the adjustmentamount is equivalent to creating a combination of the predeterminedcoordinate and the sub-coordinate. The aforementioned a and/or β can beeither positive or negative.

Further, if only one of the X coordinate or the Y coordinate needs to beamended, the adjustment amount does not need to be represented as a twovalue coordinate. For example, if only the Y coordinate of thepredetermined coordinate (x, y) needs to be amended, a combination ofthe predetermined coordinate (x, y) and the adjustment amount β can becreated. In this case, the coordinate (x, y) can be converted into thesub-coordinate (x, y+β) by adding the adjustment amount β to the Ycoordinate during the converting step.

The process of ‘adding the adjustment amount’ includes all of addition,subtraction, multiplication, division, etc. Further, the process of‘adding the adjustment amount’ is not restricted to actual calculation.For example, the process of adding the adjustment amount may be executedby loading a flag into a predetermined storage element of the computerdevice.

Each nozzle of the ink jet printer is offset in the X direction. As aresult, the dots that can be formed by one nozzle have the same Xcoordinate, and are aligned in the Y direction.

The dots formed by one nozzle tend to be displaced by the same amount inthe Y direction. For example, if dots are to be formed at (x, y1), (x,y2), and (x, y3), the dots may be formed at (x, y1+β′), (x, y2+β′), and(x, y3+β′). In this case, the dots will be formed close to (x, y1), (x,y2), and (x, y3) if an instruction is given to the printer to form thedots at, for example, (x, y1−β′), (x, y2−β′), and (x, y3−β′).

As a result, it is possible to convert all the coordinates correspondingto one nozzle into sub-coordinates by setting one adjustment amount (−β′in the above example) for the one nozzle. For example, a combination maybe created of a nozzle A and an adjustment amount α. Moreover, acombination may be created of a nozzle B and an adjustment amount β.

The nozzle and the adjustment amount may be combined directly orindirectly. For example, if the dot was to be formed by the nozzle A atthe coordinate (x, y) during the forming step, and the dot was insteadformed at (x, y+β), the combination of the nozzle A and β may be createdin the combining step. Here, β is a difference amount between the Ycoordinate (y) of the coordinate (x, y) that corresponds to the nozzle Aand the Y coordinate (y+β) of the dot formed by the nozzle A during theforming step. A combination of the difference amount and the adjustmentamount may be created in the combining step. In this example, acombination of a difference amount β and an adjustment amount (forexample, −β) may be created.

The ‘combination of the difference amount and the adjustment amount’includes a combination of a range of the difference amount and theadjustment amount. For example, a combination of a range (β1 to β2) ofthe difference amount and the adjustment amount β3 may be created.

In the present specification, a device is taught for creating print datautilized by a printer. The print data creating device comprises astorage, a choosing device and a converting device.

The storage may store a combination of a predetermined coordinate and asub-coordinate which is different from the predetermined coordinate. Adistance between the predetermined coordinate and a position of a dotformed when the printer tries to form the dot at the sub-coordinate isshorter than a distance between the predetermined coordinate and aposition of a dot formed when the printer tries to form the dot at thepredetermined coordinate.

The choosing device may choose a coordinate from bit-mapped data. Thebit-mapped data includes a plurality of combinations of a coordinate andcolor information. The choosing device chooses the coordinate based onthe color information being combined with the coordinate.

The converting device may convert the coordinate chosen by the choosingdevice into the sub-coordinate in a case where the coordinate chosen bythe choosing device has been combined with the sub-coordinate in thestorage.

The print data creating device may create print data utilized by an inkjet printer. Further, the print data creating device may utilize any ofthe aforementioned techniques.

The choosing device may choose a plurality of coordinates from thebit-mapped data. For example, (x1, y1), (x2, y2), and (x3, y3) may bechosen. For example, when the storage is storing the combination of thecoordinate (x1, y1) and the sub-coordinate (x1+α, y1+β), the convertingdevice converts the chosen coordinate (x1, y1) into the sub-coordinate(x1+α, y1+β). The converting device does not convert the coordinate (x2,y2) into a sub-coordinate that differs therefrom. Nor does theconverting device convert the coordinate (x3, y3) into a sub-coordinatethat differs therefrom. In this case, print data that includes (x1+α,y1+β), (x2, y2), and (x3, y3) may be created.

The storage may store a plurality of combinations. For example, thestorage may store the coordinate (x1, y1) and the sub-coordinate (x1+α,y1+β) as well as the coordinate (x2, y2) and the sub-coordinate (x2+α,y2+β). In this case, the converting device converts (x1, y1) and (x2,y2) into sub-coordinates, and does not convert (x3, y3) into asub-coordinate. In this case, print data that includes (x1+α, y1+β),(x2+α, y2+β), and (x3, y3) may be created.

The storage storing the combination of the coordinate and the adjustmentamount is equivalent to storing the combination of predeterminedcoordinate and the sub-coordinate.

The ink jet printer may be capable of changing a unit ink quantity, thisbeing an ink quantity discharged from one nozzle to form one dot on theprint medium.

In the case of the above example, it is possible to create print dataincluding the combination of (x1+α, y1+β) and the unit ink quantity, thecombination of (x2+α, y2+β) and the unit ink quantity, and thecombination of (x3, y3) and the unit ink quantity.

The combinations being stored in the storage may include thepredetermined coordinate and at least two neighboring sub-coordinates.For example, the combination of the coordinate (x1, y1) and thesub-coordinates (x1+α1, y1+β1), (x1+α2, y1+β2) may be included. In thiscase, the converting device may convert the coordinate (x1, y1) into thesub-coordinates (x1+α1, y1+β1) and (x1+α2, y1+β2). The print data mayhave the combination of the sub-coordinate (x1+α1, y1+β1) and a firstunit ink quantity, or the combination of the sub-coordinate (x1+α2,y1+β2) and the first unit ink quantity. The coordinate (for example,(x3, y3)) that was not converted into the sub-coordinate may be combinedwith a second unit ink quantity. In this case, the first unit inkquantity may be smaller than the second unit ink quantity.

The print data creating device may be configured separately from theprinter. In this case, the print data creating device is capable ofcommunicating with the printer by a cable or wireless. The print datacreating device outputs the print data to the printer.

Alternatively, the print data creating device may be housed within theprinter.

EMBODIMENT

An embodiment of the present invention will be described with referenceto the drawings. FIG. 1 shows a schematic diagram of a personal computer1 and an ink jet printer 2 of the present embodiment. Below, thepersonal computer 1 will be referred to simply as a PC 1. Further, theink jet printer 2 will be referred to simply as a printer 2. The PC 1and the printer 2 are connected so as to be capable of communication bymeans of a communication cable 40.

The PC 1 creates print data (to be described), and outputs this printdata to the printer 2. The PC 1 has an LCD 42 and a keyboard 43, etc.The LCD 42 displays images. A user can input instructions using thekeyboard 43. For example, the user can instruct the printer 2 to printthe image displayed on the LCD 42.

The printer 2 is a color ink jet printer. The printer 2 executes aprinting operation based on the print data output from the PC 1.

The configuration of the printer 2 will be described based on FIG. 1.The printer 2 has a paper supply portion 4 that is disposed at the leftside of the figure. The paper supply portion 4 houses printing paper Pwhich is not shown in FIG. 1, but is shown in FIG. 2. A pair of deliveryrollers 6 a and 6 b is disposed to the right of the paper supply portion4. The printing paper P housed in the paper supply portion 4 is grippedbetween the delivery rollers 6 a and 6 b and is delivered thereby towardthe right.

A printing paper conveyer 10 is disposed to the right of the papersupply portion 4. The printing paper conveyer 10 has a pair of beltrollers 7 a and 7 b, a belt 8, etc. The belt 8 is wound across the beltrollers 7 a and 7 b. The belt roller 7 a is connected to an LF motor 29(see FIG. 3). The belt roller 7 a is rotated in a clockwise direction ofFIG. 1 by driving the LF motor 29. When the belt roller 7 a rotates in aclockwise direction, the belt 8 and the belt roller 7 b follow itsrotation and rotate in a clockwise direction. When the belt 8 rotates ina clockwise direction, the printing paper P mounted on an upper face ofthe belt 8 is conveyed toward the right. Silicon processing has beenexecuted on an outer peripheral face of the belt 8.

The belt rollers 7 a and 7 b and the belt 8 are supported by a chassis16. The chassis 16 is mounted on a cylindrical member 17 disposed belowthe chassis 16. The cylindrical member 17 is capable of rotating with anaxis 18 as the center, this axis 18 being located at a position removedfrom the center of the cylindrical member 17. When the cylindricalmember 17 rotates with the axis 18 as the center, the height of an upperedge of the cylindrical member 17 changes. A guide 19 is disposed at aninner circumference of the belt 8. The guide 19 is supported by thechassis 16. The guide 19 supports the belt 8.

A pressing member 10 a is disposed slightly above the belt roller 7 a.The pressing member 10 a pushes the printing paper P towards the belt 8so as to prevent the printing paper P from rising off this belt 8. Apressing member 10 b is disposed slightly above the belt roller 7 b. Thepressing member 10 b also pushes the printing paper P towards the belt8.

A separating member 11 is disposed to the right of the belt 8. Theseparating member 11 separates the printing paper P from the upper faceof the belt 8 to which it was adhering.

A paper discharge section 5 is disposed to the right of the separatingmember 11. The paper discharge section 5 houses the printing paper Pthat has been conveyed toward the right by the belt 8.

Four ink jet heads 3 a to 3 d are located above the printing paperconveyer 10. The ink jet head 3 a has a head main body 12 a at its loweredge. The head main body 12 a has a rectangular parallelopiped shapethat extends in a perpendicular direction relative to the plane of thepage of FIG. 1. A plurality of nozzles 100 (represented by the numbers100 a to 100 h in FIG. 2) is formed in a lower face of the head mainbody 12 a. Each nozzle 100 discharges ink droplets toward the printingpaper P on the belt 8. Like the ink jet head 3 a, the other ink jetheads 3 b to 3 d each have a head main body 12 b to 12 d respectively.The ink jet head 3 a discharges magenta ink. The ink jet head 3 bdischarges yellow ink. The ink jet head 3 c discharges cyan ink. The inkjet head 3 d discharges black ink. In the present embodiment, the inkjet heads 3 a to 3 d are fixed to a printer main body (not shown).Consequently, the ink jet heads 3 a to 3 d do not move. That is, theprinter 2 of the present embodiment is a line type ink jet printer.

A space is formed between the lower faces of the head main bodies 12 ato 12 d and the upper face of the belt 8. The printing paper P istransported towards the right along this space. The printing paper Ppasses in turn below the four head main bodies 12 a to 12 d. At thisjuncture, ink of the various colors is discharged from the nozzles ofthe head main bodies 12 a to 12 d.

The configuration of the head main body 12 a will now be described indetail. Since the other head main bodies 12 b to 12 d have the sameconfiguration as the head main body 12 a, a detailed description thereofwill be omitted. FIG. 2 shows a simplified plan view of a base face (aface in which nozzles are formed) of the head main body 12 a. FIG. 2 isa diagram that has been greatly simplified, and a more complicatedarrangement of nozzles is actually adopted. Details of the configurationof the ink jet head are taught in, for example, U.S. Pat. No. 4,633,268.The contents of U.S. Pat. No. 4,633,268 may be incorporated by referenceinto the present application.

The arrow A (a Y direction) in FIG. 2 shows a direction in which theprinting paper P is conveyed. The arrow B (an X direction) is adirection orthogonal to the conveying direction A of the printing paperP. In FIG. 2, only eight nozzles 100 a to 100 h are shown. However, manymore nozzles 100 are actually formed in the head main body 12 a. Below,the number 100 will be used to represent the nozzles. In FIG. 2, eightpiezoelectric elements 120 a to 120 h are shown. Below, the number 120will be used to represent the piezoelectric elements. The piezoelectricelements 120 are formed within the head main body 12 a. The nozzles 100are mutually offset in the B direction. That is, the X coordinates ofthe nozzles 100 a to 100 h differ. Ink droplets are discharged from thenozzles 100 while the printing paper P is being moved in the Adirection. The positional relationship of the nozzles 100 and theprinting paper P does not change in the B direction. One row of dotsaligned in the A direction of the printing paper P is formed by the inkdroplets discharged from one nozzle (for example, 100 a). Eight rows ofdots may be formed by the eight nozzles 100 a to 100 h shown in FIG. 2.

As a further example, a straight line BL that extends in the B directionmay be formed by forming one dot at the same Y coordinate by each nozzle100. The straight line BL is shown by a dotted line in FIG. 2 becausethis straight line BL has not yet been formed.

Each nozzle 100 is connected with a pressure chamber (not shown). Eachpressure chamber is faced by one piezoelectric element 120. Pulsesignals are applied to the piezoelectric element 120, whereupon thepiezoelectric element 120 deforms, and pressure of the ink in thepressure chamber is increased or decreased. The ink droplets are thusdischarged from the nozzle 100. The pressure chambers, piezoelectricelements, etc. are described in detail in the aforementioned U.S. Pat.No. 4,633,268.

Returning to FIG. 1, the description of the configuration of the printer2 will be continued. The printer 2 comprises a maintenance unit 14. Themaintenance unit 14 has four caps 15 a to 15 d for covering the lowerfaces of the four head main bodies 12 a to 12 d. Further, themaintenance unit 14 comprises a purge mechanism (not shown).

The maintenance unit 14 waits in a position (the position shown inFIG. 1) below the paper supply portion 4 while the printer 2 isperforming the printing operation. When the printing operation has notbeen performed for a predetermined period, a power source of the printer2 is turned off, and the maintenance unit 14 moves to the right. Thecaps 15 a to 15 d cover the lower faces of the head main bodies 12 a to12 d.

When the maintenance unit 14 is to be moved to the right from theposition shown in FIG. 1, the cylindrical member 17 is rotated and thechassis 16 is thus lowered. When the chassis 16 is lowered, the pair ofbelt rollers 7 a and 7 b, the belt 8, and the guide 9 are also lowered.

Next, the configuration of electrical circuits of the PC 1 and theprinter 2 will be described. FIG. 3 shows a simplification of theconfiguration of the electrical circuits of the PC 1 and the printer 2.

First, the configuration of the electrical circuit of the printer 2 willbe described. The printer 2 has a control board 2 a. The control board 2a comprises a CPU 20, a ROM 21, a RAM 22, an EEPROM 23, a gate array(G/A) 24, a head drive circuit 25, a motor drive circuit 30, an imagememory 32, an interface (I/F) 33, etc. The CPU 20, ROM 21, RAM 22,EEPROM 23, and gate array 24 are all connected in a manner allowingcommunication via a bus line. The motor drive circuit 30 is connected tothe CPU 20. The head drive circuit 25, the image memory 32, and the I/F33 are connected to the gate array 24.

The CPU 20 is a one chip type microcomputer that executes controlprograms. The CPU 20 creates print timing signals and reset signals.These signals are output to the gate array 24. The ROM 21 stores thecontrol programs to be executed by the CPU 20, as well as fixed valuedata. The RAM 22 temporarily stores data. The EEPROM 23 stores data.

The gate array 24 inputs the print timing signals output from the CPU20. The gate array 24 creates signals based on print data (to bedescribed: the print data is stored in the image memory 32) and theprint timing signals. For example, the gate array 24 creates drivingsignals for driving the ink jet heads 3 a to 3 d. Further, the gatearray 24 creates a conveying clock synchronized with the drivingsignals. The gate array 24 further creates latching signals andparameter signals. The signals created by the gate array 24 are outputto the head drive circuit 25. Further, the gate array 24 stores theprint data input into the interface (I/F) 33 in the image memory 32.

The head drive circuit 25 drives the ink jet heads 3 a to 3 d based onthe signals output from the gate array 24. Specifically, the head drivercircuit 25 applies pulse signals to the piezoelectric elements of theink jet heads 3 a to 3 d. The timing at which the pulse signals areapplied, and the number of pulse signals applied, are determined basedon the signals output by the gate array 24. When one pulse signal isapplied to the piezoelectric element, one ink droplet is discharged fromthe nozzle 100 that corresponds to this piezoelectric element. With theprinter 2 of the present embodiment, the number of pulse signals forforming one dot on the printing paper P can be varied. For example, onedot can be formed by applying only one pulse signal to the piezoelectricelement. In this case, a small dot is formed. Further, one dot can beformed by applying two continuous pulse signals to the piezoelectricelement. In this case, one dot is formed from two ink droplets, and amedium dot is formed. One dot can be formed by applying three continuouspulse signals to the piezoelectric element. In this case, one dot isformed from three ink droplets, and a large dot is formed. In thepresent embodiment, in the case where one dot of the same color isformed in a predetermined area, the ratio of optical density of thelarge, medium, and small dots is 50:25:10. If the reflection rate of thepredetermined area in which the dots are formed is R, the opticaldensity can be defined as D=log₁₀ (1/R). The optical density isgenerally proportional to the number of dots. The optical density whenone large dot is formed in the predetermined area is similar to theoptical density when two medium dots are formed in the predeterminedarea. Here, ‘similar’ includes the case where these are the same. Therange of similarity is determined by experiments, etc.

The image memory 32 stores the print data (to be described). The printdata is created by the PC 1. The print data output from the PC 1 isinput to the I/F 33.

The motor drive circuit 30 drives the motor 29 based on the signalsoutput from the CPU 20. The belt rollers 7 a and 7 b, and the belt 8thus rotate.

The CPU 20 is connected with devices 28 and 31 that are disposed to theexterior of the control board 2 a. The device 28 is an operation panel.The device 31 is a paper sensor. The user can utilize the operationpanel 28 to input instructions. The instructions that have been inputare fetched to the CPU 20. The paper sensor 31 detects a tip position ofthe printing paper P that is being supplied from the paper supplyportion 4 (see FIG. 1). The paper sensor 31 outputs the detectionsignals to the CPU 20. The CPU 20 determines the timing at which inkwill be discharged from the nozzles 100 based on the detection signalsoutput from the paper sensor 31.

Next, the configuration of the electrical circuit of the PC 1 will bedescribed. The PC 1 comprises the LCD 42, the keyboard 43, a CPU 44, aROM 45, a RAM 46, a hard disc 47, an interface (I/F) 48, an I/Ointerface (I/O) 49, etc. The CPU 44 is connected to the ROM 45 and theRAM 46 via a data bus. The hard disc 47, LCD 42, and keyboard 43 areeach connected with the I/O 49. The I/O 49 is connected with theinterface 48.

The CPU 44 executes programs stored in the ROM 45 and the hard disc 47,etc. The ROM 45 stores the programs to be executed by the CPU 44. TheRAM 46 temporarily stores data. The RAM 46 has a buffer memory 46 a thatis capable of storing the information of eight lines of sub-coordinates(the sub-coordinates will be described later). The hard disc 47 is aloadable magnetism storage device. The hard disc 47 comprises a dataprocessing program 47 a, a first table 47 b, a second table 47 c, a twovalue data memory 47 d, a print data memory 47 e, etc. These programs,etc. 47 a to 47 e are stored in a recording medium (for example, aCD-ROM) that is an accessory of the printer 2. The user installs theprograms 47 a to 47 e on the PC 1. The hard disc 47 stores the programs47 a to 47 e that have been installed.

The programs 47 a to 47 e will be described in detail later. Here, asimple description thereof will be given. The data processing program 47a is a program for executing processes shown in the flowcharts of FIGS.8 to 10 (to be described). The first table 47 b stores a table of FIG. 7(to be described). The second table 47 c stores a table of FIG. 14 (tobe described). The two value data memory 47 d stores two value data (tobe described: see FIG. 11). The print data memory 47 e stores the printdata (to be described: see FIG. 16).

The I/F 48 is connected with the I/F 33 of the printer 2 via thecommunication cable 40. The PC 1 can output the print data to theprinter 2 via the I/F 48 and the I/F 33. The I/O 49 communicates databetween the I/F 48, the CPU 44, etc.

The PC 1 realizes the functions for creating the print data utilizingthe devices 42 to 49. FIG. 4 shows, in a simplified manner, thefunctions realized by the PC 1. FIG. 4 shows the configuration of aprint data creating device 70 realized by the PC 1. The print datacreating device 70 comprises a bit-mapped data creating portion 72, acoordinate choosing portion 74, a coordinate converting portion 76, anoutputting portion 78, and a memory 80. The functions of the portions 72to 80 are described later in detail using the flowcharts of FIGS. 8 to10. Here, the functions of the portions 72 to 80 will be describedsimply. The bit-mapped data creating portion 72 executes the process ofconverting, for example, an image displayed on the LCD 42 intobit-mapped data. Further, the bit-mapped data creating portion 72executes the process of enlarging or reducing the bit-mapped data sothat it will match the resolution of the printer 2. Moreover, thebit-mapped data creating portion 72 executes the process of adjustingcolor information of the bit-mapped data. The coordinate choosingportion 74 chooses coordinates at which dots will be formed from all thecoordinates of the bit-mapped data. The coordinate converting portion 76converts the coordinates chosen by the coordinate choosing portion 74into sub-coordinates. The outputting portion 78 outputs, to the printer2, the print data that includes information showing the sub-coordinatesconverted by the coordinate converting portion 76. The memory 80functions as a memory for storing the first table 47 b and the secondtable 47 c (see FIG. 3). Further, the memory 80 functions as the memory47 d for storing the two value data and the memory 47 e (see FIG. 3) forstoring the print data. Moreover, the memory 80 functions as the buffer46 a (see FIG. 3).

Next, the method will be shown of manufacturing the recording medium(the computer program product) that is installed on the hard disc 47 ofthe PC 1. FIG. 5 shows a flowchart of a manufacturing process.

When the ink jet printer 2 has been manufactured, the straight line BL(see FIG. 2) extending in the B direction is formed in the printer 2(S2). This process is executed for each of the four ink colors. That is,the process of S2 is executed using each of the ink colors cyan,magenta, yellow, and black. When the cyan straight line BL is formed,each nozzle 100 of the head main body 12 a forms one dot. Similarly,when the straight lines BL of the other colors are formed, each nozzle100 of the head main bodies 12 b to 12 d forms one dot.

The process of S2 is executed by supplying the printer 2 with print datathat instructs the formation of the straight line BL. This print dataincludes information instructing dots to be formed at, for example, thecoordinates (x, y), (x+s, y), (x+2s, y), (x+3s, y) . . . .

Next, a difference amount between each of the dots and a base line ismeasured (S4). This step is performed for each of the straight lines BLof cyan, magenta, yellow, and black. The base line is a hypotheticalline showing the position at which the straight line BL should be formedby the printer 2. FIG. 6 (a) shows the base line and a part of thestraight line BL formed in S2. In FIG. 6 (a), the centers of the dots(large dots) are aligned in a row on the base line, and could be termedan ideal straight line BL. Since eight dots are formed in FIG. 6 (a),eight nozzles are required. In FIG. 6 (a), X coordinates of the nozzlesfor forming the eight dots are shown by the numbers 1 to 8. FIG. 6 (b)shows dots that have been formed in positions displaced from the baseline. FIG. 6 (b) shows three straight lines which are the base line, thebase line +1.0, and the base line −1.0. The space between the base lineand the base line +1.0 is equivalent to the space between the base lineand the base line −1.0. When a large dot is formed on the base line anda large dot is formed at the base line +1.0 (or at the base line −1.0),these two large dots make contact. That is, the space between the baseline and the base line +1.0 (or the base line −1.0) is equivalent to adiameter of the large dot.

The arrow A in the figure shows the conveying direction of the printingpaper P. The dots formed by the nozzles which have the X coordinates 3,4, and 8 are formed above the base line. Further, the dots formed by thenozzles which have the X coordinates 5 and 6 are formed below the baseline. The dots formed by the nozzles which have the X coordinates 1, 2,and 7 are formed on the base line.

When the straight line BL shown in FIG. 6 (a) is formed, the differenceamount between each dot and the base line in S4 is specified as zero.Furthermore, when the straight line BL shown in FIG. 6 (b) is formed,the difference amount between the dot and the base line in S4 isspecified for each nozzle. In the present embodiment, the differenceamount is a minus amount when the dots are formed above the base line,and the difference amount is a plus amount when the dots are formedbelow the base line. For example, in the case of the nozzle which hasthe X coordinate 3, the difference amount between the dot and the baseline can be specified as −0.7. As another example, in the case of thenozzle which has the X coordinate 5, the difference amount between thedot and the base line can be specified as +0.1.

In the present embodiment, the process of S4 is executed manually. Forexample, the process can be executed as follows. (1) the printing paperP on which the straight line BL has been formed is read by a scanner(for example, a CCD). (2) The image that has been read is shown on adisplay. It is preferred that this is enlarged and displayed. The dotsthat comprise the straight line BL are shown on the display, and the Xcoordinates of the nozzles and the base lines are shown on the display.In this case, the contents in the example of FIG. 6 (b) are shown. (3)The difference amount between the base line and the dot is estimated byeye for each dot (i.e. for each nozzle). Although the process of S4 isexecuted manually in the present embodiment, the process of S4 mayequally be executed utilizing a machine.

The process of S4 is executed for each of the four colors. Thedifference amount is measured for all the nozzles 100 of the head mainbody 12 a. Similarly, the difference amount is measured for all thenozzles 100 of the head main bodies 12 b to 12 d. In the presentembodiment, there is a difference amount only in a part of the nozzles100 of the head main body 12 a that corresponds to the cyan ink. Thatis, the straight lines BL formed by the head main bodies 12 b to 12 dare formed on the base line. The difference amount of the nozzles of thehead main bodies 12 b to 12 d is zero.

The process of S6 is executed after the process of S4 has been executed.In S6, the first table 47 b which has combinations of the X coordinatesof the nozzles and the difference amounts is created. FIG. 7 shows anexample of contents stored in the first table 47 b. FIG. 7 stores thedifference amounts for the nozzles 100 of the head main body 12 a thatcorresponds to the cyan ink. The contents of FIG. 7 correspond to thecontents of FIG. 6 (b). That is, the difference amount for the Xcoordinates 1, 2, and 7 shown in FIG. 6 (b) is zero. Consequently, thedifference amount for the X coordinates 1, 2, and 7 in FIG. 7, also, iszero. Further, in FIG. 6 (b), the difference amount is −0.7 for the Xcoordinate 3. The difference amount is −0.2 for the X coordinate 4. Thedifference amount is +0.1 for the X coordinate 5. The difference amountis +0.7 for the X coordinate 6. The difference amount is −0.3 for the Xcoordinate 8. Difference amounts corresponding to this are shown in FIG.7.

In the process of S6, the first tables 47 b that correspond to each ofthe four head main bodies 12 a to 12 d are formed. In the presentembodiment, the first tables 47 b that correspond to the head mainbodies 12 b to 12 d all have a difference amount of zero for each of thenozzles.

The process of S8 is executed after the process of S6 has been executed.In the process of S8, a program is loaded onto a recording medium suchas a CD-ROM or the like. Here, the data processing program 47 a, thefirst table 47 b, and the second table 47 c, all shown in FIG. 3, areloaded onto the recording medium. The first table 47 b formed in S6 isloaded onto the recording medium. The second table 47 c is fixedinformation, and is not a table set in accordance with the processes ofS2 to S6. An example of the contents stored in the second table 47 c isshown in FIG. 14. Combinations of the range of the difference amount andsub-coordinates are stored in the second table 47 c. That is,sub-coordinates for adjusting the difference amount of the nozzles canbe stored. The second table 47 c may be formed when the steps of S6 andS8 are executed. Alternatively, the second table 47 c may be formed inadvance. The contents of the second table 47 c will be described indetail later.

Moreover, in S8, a program is written for maintaining storage areas ofthe two value data memory 47 d, the print data memory 47 e, and thebuffer memory 46 a (all in FIG. 3) in the PC 1.

The computer program product (for example, a CD-ROM) is completed byexecuting the above processes S2 to S8, this computer program productincluding instructions for ordering the PC 1 to form the print data. Thecompleted computer program product is an accessory of the printer 2.

The data processes executed by the PC 1 will be described with referenceto FIGS. 8 to 10. FIG. 8 shows a flowchart of the processes for creatingand outputting the print data. The data process is executed by the printdata creating device 70 of FIG. 4.

The user can designate desired image data (this includes text data) andinstruct printing the image data. The user can input the instructionusing the keyboard 43 (see FIG. 3). When the instruction is input, thedata processing program 47 a shown in FIG. 3 is executed, and theprocesses shown in FIG. 8 are thus executed.

The print data creating device 70 first executes a rasterization process(S20) on the image data instructed by the user. The image data is thusconverted into bit-mapped data. The bit-mapped data comprises aplurality of pixel data. Each pixel datum is a combination of acoordinate obtained by subdividing the image data into a matrix shape,and color information at this coordinate. The color information isrepresented by color density (this may be termed a gradation value) foreach of the four colors (cyan (C), magenta (M), yellow (Y), and black(K)). As a result, one pixel datum includes a combination of onecoordinate, C color density, M color density, Y color density, and Kcolor density. In the case where image data in which bit-mapped data hasalready been created is to be printed, the process of S20 can beskipped.

Next, the bit-mapped data created in S20 is enlarged or reduced (S22).The bit-mapped data is thus rewritten to match the resolution of theprinter 2. In the present embodiment, the bit-mapped data is convertedto a resolution of 600 dpi (dots per inch)×600 dpi. Here, thecoordinates before rewriting are rewritten into coordinates that matchthe aforementioned resolution.

Performing the process of S22 creates the need to adjust the colorinformation of the pixel data that has been rewritten. The colorinformation of the pixel data that has been rewritten must be determinedsuch that, as far as possible, there is no loss of the color informationof the pixel data from prior to rewriting. The process of S24 isexecuted to achieve this. The contents of the process of S24 are taughtin, for example, U.S. Pat. No. 6,757,076. The contents of U.S. Pat. No.6,757,076 may be incorporated by reference into the present application.

When the process of S24 is completed, the bit-mapped data in which thecolor information has been adjusted is created. A plurality of pixeldata is included in this bit-mapped data. Each pixel datum includes acombination of one coordinate, cyan color density, magenta colordensity, yellow color density, and black color density.

The processes of S20 to S24 are executed by the bit-mapped data creatingportion 72 of FIG. 4.

Next, a halftone process is executed (S26). Here, the coordinates atwhich the dots will be formed are chosen from the bit-mapped data. Thisprocess is executed based on the color information (the color density ofthe four colors) of the pixel data. An example of the process of S26 isgiven below. The color density of each of the four colors included inthe color information of the pixel datum is compared with apredetermined threshold by the print data creating device 70. Forexample, in the case where the color density is represented by anydensity between 0 and 255,128 can be adopted as the threshold. If, forexample, the cyan color density included in the pixel datum is 200, thecoordinate (for example, (x1, y1)) included in that pixel datum ischosen in S26. In this case, information in which the chosen coordinate(x1, y1) and cyan are matched is stored. Specifically, the combinationof the coordinate (x1, y1), cyan, and a flag ‘1’ is stored in the twovalue data memory 47 d of FIG. 3. As another example, if the magentacolor density combined with the coordinate (x1, y1) is 100, thecombination of the coordinate (x1, y1), magenta, and a flag ‘0’ isstored. Below, the flag ‘1’ may represent the flag ON, and the flag ‘0’may represent the flag OFF. If at least two color densities included inone pixel datum exceed the threshold, the flag is turned ON for thecolor that has the greatest color density, and the flag is turned OFFfor the other colors. For example, if one pixel datum includes thecombination of the coordinate (x1, y1), cyan color density of 200,magenta color density of 100, yellow color density of 150, and blackcolor density of 50, then the following combinations are created: thecombination of the coordinate (x1, y1), cyan, and the flag ‘1’; thecombination of the coordinate (x1, y1), magenta, and the flag ‘0’; thecombination of the coordinate (x1, y1), yellow and the flag ‘0’; and thecombination of the coordinate (x1, y1), black, and the flag ‘0’.Furthermore, if at least two color densities included in one pixel datumexceed the threshold, the flags corresponding to two colors may both beturned ON.

If the gradation value of all the four colors combined with onecoordinate is smaller than 128, all the four flags corresponding to thatcoordinate are turned OFF. In this case, that coordinate has not beenchosen in S26.

When the above process has been executed on all the pixel data, and thecoordinates at which the dots are to be formed have been chosen, theprocess proceeds to S28. Below, one item of information corresponding toone flag (the information of the combination of coordinate, color, and‘1’ or ‘0’) is also termed pixel datum. Consequently, when the processof S26 is executed, a plurality of pixel data is created. The pluralityof pixel data created in S26 is termed two value data.

The process described above is one example of the halftone process, andthis example does not necessarily have to be executed. For example, theerror diffusion method or the dither method may equally well beutilized. These methods are taught in, for example, U.S. Pat. Nos.4,760,460 and 4,521,805. The contents of U.S. Pat. Nos. 4,760,460 and4,521,805 may be incorporated by reference into the present application.

Moreover, the halftone process is not restricted to having the twovalues of the flag being on or off. The halftone process can bequantized to three or more. For example, the process can be quantized tofour values: large dot on, medium dot on, small dot on, and dot off.

The halftone process of S26 is executed by the coordinate choosingportion 74 of FIG. 4.

FIG. 11 shows an example of the two value data. This two value datacorresponds to cyan. The two value data corresponding to the othercolors is created in the same way in S26. Below, the left-rightdirection of FIG. 11 is an X axis direction (Row) and the up-downdirection of FIG. 11 is a Y axis direction (Line). The X axis directionof FIG. 11 corresponds to the X axis direction of other figures, and theY axis direction of FIG. 11 corresponds to the Y axis direction of otherfigures. The row numbers of FIG. 11 correspond to the numbers (the Xcoordinates of the nozzles) of FIG. 7.

As shown in FIG. 11, each pixel datum of the two value data stores ‘1’or ‘0’. For example, ‘1’ is stored corresponding to the coordinate (1,M), and ‘0’ is stored corresponding to the coordinate (1, M+1). In thepresent embodiment, a distance (1) between the Y coordinate (M) and theY coordinate (M+1) of the two value data is equivalent to a distance(4t; See FIG. 13 for t) between two adjoining base lines of FIG. 6 (b).

Below, one line of data of the two value data is termed one line data.In FIG. 11, three items of one line data are shown: the line M, the lineM+1, and the line M+2.

When the halftone process of S26 of FIG. 8 has been completed, theprocess proceeds to S28. The process of S28 is executed by thecoordinate converting portion 76 of FIG. 4. The print data creatingprocess of S28 will be described with reference to FIGS. 9 and 10. FIGS.9 and 10 show flowcharts of the print data creating process of S28.Here, the process that is executed on the basis of the two value datacorresponding to cyan is described. Similar processes are executed forthe other colors.

In the print data creating process, the buffer memory 46 a (see FIG. 3)is first initialized (S50). FIG. 12 shows an example of the buffermemory 46 a that has been initialized. The buffer memory 46 a can storecombinations of the sub-coordinates (to be described) and scale of dots.The buffer memory 46 a can store information about the sub-coordinatesobtained from one line data. In the present embodiment, information ofeight lines of sub-coordinates is obtained from one line data. Thispoint will be described in detail later. Below, the four lines from ‘−4’to ‘−1’ in FIG. 12 will be termed an upper storage region 46 au. Thefour lines from ‘0’ to ‘3’ will be termed a lower storage region 46 ad.The row numbers of the buffer memory 46 a (shown by 1 to 8 in FIG. 12)correspond to the row numbers of the two value data (see FIG. 11).

When the buffer memory 46 a has been initialized in S50 in FIG. 9, theone line data included in the two value data (see FIG. 11) is read(S52). For example, the one line data for the line M is read. Next, theone pixel datum included in the one line data that was read in S52 isread (S54). In the example of FIG. 11, the pixel datum having thecombination of the coordinate (1, M) and the flag ‘1’ is read. Then, itis determined whether the flag is ON of the pixel datum read in S54(S56). For example, in the case where the pixel datum read in S54 hasthe combination of the coordinate (1, M) and the flag ‘1’, YES isdetermined in S56. If S56 is YES, the process proceeds to S58. In thecase where, for example, the pixel datum read in S54 has the combinationof the coordinate (2, M) and the flag ‘0’, NO is determined in S56. IfS56 is NO, the process proceeds to S64.

When YES was determined in S56, the difference amount is read (S58) fromthe first table 47 b (see FIG. 7). The first table 47 b is retrieved byusing the X coordinate of the coordinate read in S54 as a key. Thedifference amount can thus be specified. In FIG. 7, for example, thereis the combination of the X coordinate (1) and the difference amount(0). Consequently, if the combination of the coordinate (1, M) and theflag ‘1’ is read in S54, a difference amount (0) is specified in S58.Further, in FIG. 7, there is the combination of the X coordinate (4) andthe difference amount (−0.2). Consequently, if the combination of thecoordinate (4, M) and the flag ‘1’ is read in S54, a difference amount(−0.2) is specified in S58.

When the difference amount has been read in S58, the sub-coordinates arespecified (S60) based on the second table 47 c. The sub-coordinates arecoordinates in the neighborhood of the coordinates of the pixel dataread in S54.

The sub-coordinates will be described with reference to FIG. 13. FIG. 13(a) shows a coordinate P (x, y) included in one pixel datum. In FIG. 13,one coordinate is represented by one dot. FIG. 13 (b) shows eightsub-coordinates p−4 to p3 that correspond to the coordinate (x, y). Thedirection A in the figure is the direction in which the printing paper Pmoves relative to the ink jet heads 3 a to 3 d. The sub-coordinate p0(x, y) of the present embodiment is the same as the coordinate P (x, y)included in the pixel datum. The sub-coordinates p−4 to p3 are alignedin the direction in which the printing paper P moves relative to the inkjet heads 3 a to 3 d. A small number is adopted as ‘t’ shown in FIG. 13(b). As a result, if dots were to be formed at all of thesub-coordinates p−4 to p3, the major part of each dot would overlap withthe adjoining dot. In the present embodiment, t is equivalent to alength one eighth the distance between the base line −1.0 and the baseline +1.0 (see FIG. 6 (b)). Consequently, if the distance between thebase line −1.0 (or the base line +1.0) and the base line is 1, then t is0.25. The length t is equivalent to one fourth the diameter of one largedot.

The difference amounts are divided into fifteen ranges in the secondtable 47 c as shown in FIG. 14. Further, the numbers −4 to 3 correspondto the sub-coordinates p−4 to p3. Either an empty column, or 2 or 3 areshown in the cells specified by one range of the difference amount andone sub-coordinate. The number 2 in the cell corresponds to a mediumdot, and the number 3 in the cell corresponds to a large dot. The secondtable 47 c stores a plurality of combinations of the range of differenceamount, the sub-coordinate, and the scale of the dot. For example, thecombination of the range of the difference amount (−0.5625 to −0.4375),the sub-coordinate p2 and a large dot is stored. Moreover, theinformation for small dots may also be stored in the table of FIG. 14.In that case, the number ‘1’ may be adopted to correspond to the smalldot.

In S60 of FIG. 9, a combination of the sub-coordinate and the scale ofthe dot is specified based on the difference amount read in S58 and thesecond table 47 c. For example, if the difference amount (−0.2) was readin S58, the combination of the sub-coordinate p1 and a large dot isspecified. If the difference amount read in S58 was zero, thecombination of the sub-coordinate p0 and a large dot is specified. Asshown in FIG. 13, the sub-coordinate p0 is a coordinate that isidentical with the coordinate that has been read. In S60, twosub-coordinates may be specified from one difference amount. Forexample, if the difference amount (+0.1) was read, the combination ofthe sub-coordinate p−1 and a medium dot, and the combination of thesub-coordinate p0 and a medium dot are specified.

Next, the information specified in S60 is written into the buffer memory46 a (see FIG. 3) (S62). The process of S62 will be described withreference to FIG. 15. FIG. 15 (a) to (f) shows a time sequence ofchanges of contents stored in the buffer memory 46 a. In FIG. 15 (a) to(f), the numbers ‘−4’ to ‘3’ that are aligned in a vertical directioncorrespond to the sub-coordinates p−4 to p3. Furthermore, the numbers‘1’ to ‘8' that are aligned in a horizontal direction correspond to therow numbers (the X coordinates of the nozzles) of the two value data.

As an example, the case will be described where the difference amount(−0.2) was read in S58. In this case, the combination of thesub-coordinate p−1 and ‘3’ (a large dot) is specified in S60. In thiscase, ‘3’ is written into the cell that corresponds with the row number4 and the sub-coordinate p1. In FIG. 15, ‘3’ has been written into thecell that corresponds with the row number 4 and the sub-coordinate p1.Further, as an example, the case will be described where the differenceamount (+0.1) was read in S58. In this case, a combination of thesub-coordinate p−1 and ‘2’ (a medium dot) and the combination of thesub-coordinate p0 and ‘2’ (a medium dot) are specified in S60. In thiscase, ‘2’ is written into the cell that corresponds with the row number5 and the sub-coordinate p0, and ‘2’ is written into the cell thatcorresponds with the row number 5 and the sub-coordinate p−1.

When the process of S62 of FIG. 9 has been completed, the processproceeds to S64. When NO was determined in S56, also, the processproceeds to S64. Since the processes from S58 to S62 were skipped whenNO was determined in S56, all the eight cells (the eight verticallyaligned cells) for one row number in the buffer memory 47 a remain atzero.

In S64, it is determined whether the processes S54 to S62 were executedfor all the pixel data included in the one line data read in S52. WhenYES is determined, the process proceeds to S80 of FIG. 10. When NO isdetermined in S64, the process returns to S64 and one pixel datum isread.

FIG. 15 (a) shows the contents stored in the buffer memory 46 a when theprocesses S54 to S62 have been executed for all the pixel data includedin the one line data of the line M shown in FIG. 11. In FIG. 15 (a), thenumbers 2 or 3 have been stored in six cells.

Next, the processes after S80 will be described with reference to FIG.10. In S80, the values in the upper storage region 46 au (−4 to −1) ofthe buffer memory 46 a are written into the print data memory 47 e. FIG.16 shows an example of the print data memory 47 e. The row numbers ofthe print data memory 47 e (1 to 8 are shown in FIG. 16) correspond tothe row numbers of the FIG. 15. The left-right direction of the printdata memory 47 e is an X axis direction, and the up-down direction is aY axis direction. A combination of the X coordinate and the Y coordinatecan be represented by each cell in the print data memory 47 e. In FIG.16, the X coordinates 1 to 8 are shown. Further, the Y coordinates M −4tto M+3−t are shown. As described above, t is 0.25. As a result, the Ycoordinate (M+1−4t) is equivalent to the Y coordinate (M). The values inthe upper storage region 46 au (−4 to −1) of FIG. 15 (a) are writteninto a block D1 of the print data memory 47 e. By this process, theinformation of the sub-coordinates p−4 to p−1 of the one line data ofthe line M is written into the print data memory 47 e. At this stage,the information of the sub-coordinates p0 to p3 of the one line data ofthe line M is not written into the print data memory 47 e.

Next, the stored contents of the lower storage region 46 ad of thebuffer memory 46 a are shifted (S82), while maintaining their sequence,to the upper storage region 46 au. Specifically, the values of the cellsof the line 0 are shifted to the cells of the line −4, the values of thecells of the line 1 are shifted to the cells of the line −3, the valuesof the cells of the line 2 are shifted to the cells of the line −2, andthe values of the cells of the line 3 are shifted to the cells of theline −1. FIG. 15 (b) shows how the lower storage region 46 ad of FIG. 15(a) has been shifted to the upper storage region 46 au by executing theprocess of S82.

When the process of S82 has been executed, the lower storage region 46ad of the buffer memory 46 a is initialized (S84). In FIG. 15 (b), allof the cells in the lower storage region 46 ad have been initialized tozero.

Next, it is determined whether all the one line data of the two valuedata (see FIG. 11) has been processed (S86). If NO is determined, theprocess returns to S52 of FIG. 9, and other one line data is read. Ifthe process has been completed for the one line data of the line M, theone line data of the line M+1 is read.

FIG. 15 (c) shows the buffer memory 46 a when the processes S54 to S62have been executed for the one line data of the line M+1. In FIG. 15(c), the information for the case where the processes have beenperformed for the one line data of the line M+1 is added to the buffermemory 46 a of FIG. 15 (b). The information of the sub-coordinates p0 top3 for the case where the processes have been performed for the one linedata of the line M+1 is stored in the lower storage region 46 ad of FIG.15 (c). The upper storage region 46 au of the buffer memory 46 a storesa combination of the information of the sub-coordinates p0 to p3 whenthe processes have been performed for the one line data for the line M,and the information of the sub-coordinates p−4 to p−1 when the processeshave been performed for the one line data of the line M+1. For example,the ‘3’ in the cell specified by the sixth line and the sub-coordinatep−3 in the upper storage region 46 au of FIG. 15 (c) is the contentstored in the case where the processes have been performed for the oneline data of the line M+1. The other cells of ‘2’ or ‘3’ in the upperstorage region 46 au are information of the sub-coordinates p0 to p3when the processes have been performed for the one line data of the lineM.

The contents stored in the upper storage region 46 au of FIG. 15 (c) arewritten into a block D2 (see FIG. 16) of the print data memory 47 e(S80). The information of all the sub-coordinates p−4 to p3 of the oneline data of the line M is thus written. Further, the information of thesub-coordinates p−4 to p−1 of the one line data of the line M+1 iswritten.

As described above, the buffer memory 46 a stores only the informationof the eight lines worth of sub-coordinates. That is, all theinformation of the sub-coordinates corresponding to all the one linedata can not be stored. Consequently, the Y coordinates of thesub-coordinates cannot be specified based only on the information of thebuffer memory 46 a. For example, the X coordinate can be specified fromthe information ‘2’ of the sub-coordinate p−1 of the fifth row of FIG.15 (a), but the Y coordinate cannot be specified.

The sub-coordinates corresponding to one line data are stored by writingthe information of the buffer memory 46 a into the blocks of the printdata memory 47 e. For example, the Y coordinate (M−t) can be specifiedby writing the information ‘2’ of the sub-coordinate p−1 of the fifthrow of FIG. 15 (a) into the block D1 of the print data memory 47 e. Theinformation stored in the buffer memory 46 a could be said to beadjustment amounts for converting the Y coordinates of the coordinatesincluded in one line data. The action of writing the information of thebuffer memory 46 a into the print data memory 47 e is equivalent to theaction of adding the adjustment amount to the coordinate chosen in S26of FIG. 8 and thus converting it into the sub-coordinate. The action ofspecifying the sub-coordinate in S60 of FIG. 9 is equivalent to theaction of specifying the adjustment amount corresponding to thedifference amount. The adjustment amount that has been specified isstored in the buffer memory 46 a. By means of writing the informationfrom the buffer memory 46 a into the print data memory 47 e, theadjustment amount is added to the coordinate read in S54, thus thecoordinate read in S54 is converted into the sub-coordinate.

When the difference amount corresponding to the coordinate read in S54is zero, a sub-coordinate which is the same as the coordinate isspecified in S60. That is, it could be said that the coordinatecorresponding to the nozzle having the difference amount of zero is notconverted to a differing sub-coordinate.

FIG. 15 (d) shows the results when the processes of S82 to S84 have beenperformed on the buffer memory 46 a of FIG. 15 (c). The information ofthe sub-coordinates p0 to p3 when the processes of S54 to S64 have beenperformed for the one line data of the line M+1 is stored in the upperstorage region 46 au of the buffer memory 46 a.

FIG. 15 (e) shows the buffer memory 46 a when the processes of S54 toS62 have been performed for the data of the line M+2. The upper storageregion 46 au of FIG. 15 (e) includes the information of thesub-coordinates p0 to p3 when the processes of S54 to S62 have beenperformed for the one line data of the line M+1, and the information ofthe sub-coordinates p−4 to p−1 when the processes of S54 to S62 havebeen performed for the one line data of the line M+2. The lower storageregion 46 ad of FIG. 15 (e) includes the information of thesub-coordinates p0 to p3 when the processes of S54 to S62 have beenperformed for the one line data of the line M+2. The contents stored inthe upper storage region 46 au of FIG. 15 (e) are written into a blockD3 of the print data memory 47 e (S80).

FIG. 15 (f) shows the results when the processes of S82 to S84 have beenperformed on the buffer memory 46 a of FIG. 15 (e). The information ofthe sub-coordinates p0 to p3 when the processes of S54 to S62 have beenperformed for the one line data of the line M+2 is stored in the upperstorage region 46 au.

If YES is determined at S86 of FIG. 10, the process proceeds to S88. InS88, the information of the upper storage region 46 au of the buffermemory 46 a is written into the print data memory 47 e. For example, inthe case where the one line data of the line M+2 is the final one linedata, the information in the upper storage region 46 au of FIG. 15 (f)is written into a block D4 (see FIG. 16) of the print data memory 47 e.When the process of S88 has been executed, the print data creatingprocess (S28) of FIG. 8 is completed.

The process of S28 was described in detail using the case of creatingcyan print data as an example. The print data can be created for theother colors by executing processes similar to the case for cyan.

The print data for each color includes a plurality of combinations ofthe coordinate and scale of the dot. For example, in the print datacorresponding to cyan shown in FIG. 16, there is the combination of thesub-coordinate (5, M−t) and ‘2’ (medium dot). This sub-coordinate (5,M−t) has been converted from the coordinate (5, M) of the two value datashown in FIG. 11. Further, in FIG. 16, there is the combination of thesub-coordinate (1, M+1−4t) and ‘3’ (large dot). This sub-coordinate (1,M+1−4t) is equivalent to the coordinate (1, M) of the two value datashown in FIG. 11. That is, it could be said that the sub-coordinate (1,M+1−4t) is not a coordinate which has been obtained by the conversion.

When the print data has been created, the process proceeds to S30 ofFIG. 8. In S30, a print command is added to the print data created inS28. The print command is a command that follows settings to cause theprinter 2 to perform printing.

When S30 has been completed, the print data to which the print commandhas been added is output to the printer 2 (S32). The process of S32 isexecuted by the outputting portion 78 of FIG. 4.

When the print data output from the PC 1 has been input to the printer2, the printer 2 performs the printing operation based on the printdata. The printer 2 discharges ink from the nozzles based on the printdata. Specifically, the printer 2 applies pulse signals to thepiezoelectric elements 120 (see FIG. 2) based on the print data. Forexample, if the print data includes the combination of thesub-coordinate (1, M+1−4t) and ‘3’ (large dot), as shown in FIG. 16, alarge dot is formed at the coordinate (1, M+1−4t), i.e. the coordinate(1, M). Three continuous pulse signals are applied to the piezoelectricelement 120 in order to form the large dot. The nozzle 100 for formingthe large dot at the coordinate (1, M) has a difference amount of zero(see the row number 1 of FIG. 7). As a result, a large dot is formed atthe coordinate (1, M). Two continuous pulse signals are applied to thepiezoelectric element 120 in order to form a medium dot, and one pulsesignal is applied to the piezoelectric element 120 in order to form asmall dot.

As another example, the nozzle 100 for forming a dot at the coordinate(4, M) of the two value data has a difference amount of (−0.2) (see rownumber 4 of FIG. 7). As a result, when the printer 2 tries to form a dotat the coordinate (4, M), a dot is formed in the neighborhood of thecoordinate (4, M−0.2). In this case, the dot is formed at a positionthat is separated by a large distance from the coordinate (4, M) wherethe dot was desired. In the present embodiment, the coordinate (4, M) ofthe two value data of FIG. 11 is converted into the sub-coordinate (4,M+1 −3t). The print data includes the combination of (4, M+1−3t) and ‘3’(large dot) (see FIG. 16). The printer 2 tries to form a large dot atthe coordinate (4, M+1−3t), i.e. at the coordinate (4, M+0.25). In thiscase, the dot is formed in the neighborhood of the coordinate (4,M+0.05). This coordinate is close to the coordinate (4, M) of the twovalue data.

The printer 2 does not form dots at sub-coordinates that are combinedwith ‘0’ in the print data. For example, a cyan dot is not formed at thecoordinate (1, M−t) in FIG. 16.

The printer 2 forms the dots at the coordinates based on the informationincluded in the print data. The images instructed by the user are thusprinted on the printing paper P.

FIG. 17 (a) shows an example of dots formed when the present embodimenthas not been adopted. That is, FIG. 17 (a) shows an example of dotsformed by the printer 2 based on the two value data of FIG. 11. FIG. 17(b) shows an example of dots formed when the present embodiment has beenadopted. The row numbers (the X coordinates) in FIG. 17 (a) and (b)correspond to the row numbers (the X coordinates) in FIG. 11 and FIG.16. Furthermore, M, M+1, and M+2 in FIG. 17 (a) and (b) correspond tothe Y coordinates in FIG. 11 and FIG. 16.

As shown in FIG. 17 (a), the dots are not formed at the desired Ycoordinates (M, M+1, M+2) when the present embodiment has not beenadopted.

In the present embodiment, when the two value data (see FIG. 11)consists of one line data of a line ‘a’, the print data consists of dataof a sub-coordinate of line (4a+4). Consequently, the printer 2 executesthe printing operation such that resolution in the Y axis direction (thedirection in which the printing paper P is conveyed) is about four timesof the two value data. For example, if the resolution of the two valuedata in the Y axis direction is 600 dpi, the printing operation isexecuted such that resolution in the Y axis direction is 2400 dpi.

Further, in the present embodiment, the sub-coordinates (p−4, p−3, p−2,p−1) and the sub-coordinates (p0, p1, p2, p3) are combined in the buffermemory 46 a in S82 of FIG. 10. This makes it possible to easily createprint data when the printer 2 includes nozzles corresponding to the plusdifference amount as well as nozzles corresponding to the minusdifference amount.

There were eight sub-coordinates in the present embodiment. If thenumber of sub-coordinates is increased, the difference amount of thenozzles can be adjusted by small units. For example, if a sub-coordinatep′ is formed between the sub-coordinate p2 and the sub-coordinate p3, itis possible to adjust a difference amount that is between the differenceamount that can be adjusted by the sub-coordinate p2 and the differenceamount that can be adjusted by the sub-coordinate p3. However, if thenumber of sub-coordinates is increased, the amount of data is alsoincreased. To deal with this, one coordinate is converted into twosub-coordinates in the present embodiment. For example, if a nozzlecorresponding to a certain coordinate has a difference amount between−0.6875 and −0.5626, the certain coordinate is converted into twoadjoining sub-coordinates p2, p3 (see FIG. 14). In this case, theprinter 2 executes the printing operation such that a medium dot isformed at each of the sub-coordinates p2 and p3. For example, two mediumdots are formed in the neighborhood of the coordinate (5, M) of FIG. 17(b). The optical density of these two medium dots is similar to theoptical density of one large dot. As a result, one large dot appears tobe formed at a center of the two medium dots. In the present embodiment,medium dots are formed at two adjacent sub-coordinates (for example, p2and p3), and consequently a large dot appears to be formed at the centerof the two medium dots. The same effect can be achieved by forming thesub-coordinate p′ between the sub-coordinate p2 and the sub-coordinatep3. In the present embodiment, the difference amount of the nozzles canbe adjusted by small units using a small number of sub-coordinates.

Representative modifications to the aforementioned embodiment will nowbe described.

(1) In the representative embodiment, the buffer memory 46 a is composedof the upper storage region 46 au and the lower storage region 46 ad.The upper storage region 46 au stores data of four lines ofsub-coordinates, and the lower storage region 46 ad also stores data offour lines of sub-coordinates. Line number x which is composed of theupper storage region 46 au and line number y which is composed of thelower storage region 46 ad can be varied. For example, the upper storageregion 46 au can be made a region showing the line numbers ‘−4’ to ‘0’(x=5). In this case, the lower storage region 46 ad is a region showingthe line numbers ‘1’ to ‘3’ (y=3).

(2) In the representative embodiment, when one coordinate is convertedinto two sub-coordinates, a medium dot is combined with onesub-coordinate, and a medium dot is combined with the other secondsub-coordinate. However, a variant is possible where, for example, amedium dot is combined with the one sub-coordinate, and a small dot iscombined with the other sub-coordinate. These two dots (the medium dotand the small dot) are similar to one large dot.

(3) In the halftone process (S26), the pixel data can be createdadopting at least three values (for example, the four values of a largedot, a medium dot, a small dot, and zero). In this case, for example, ifone pixel datum having the combination of the coordinate (x, y) and amedium dot is converted into one sub-coordinate (x, y+β), thecombination of the sub-coordinate (x, y+β) and a medium dot may bestored in the print data memory 47 e. As another example, if one pixeldatum having the combination of the coordinate (x, y) and a medium dotis converted into two sub-coordinates (x, y+β1) and (x, y+β2), thecombination of the sub-coordinate(x, y+β1) and a small dot, and thecombination of the sub-coordinate (x, y+β2) and a small dot may bestored in the print data memory 47 e.

As another example, if one pixel datum having the combination of thecoordinate (x, y) and a small dot is converted into one sub-coordinate(x, y+β), the combination of the sub-coordinate (x, y+β) and a small dotmay be stored in the print data memory 47 e. As another example, if onepixel datum having the combination of the coordinate (x, y) and a smalldot is converted into two sub-coordinates (x, y+β1) and (x, y+β2), thecombination of either of the sub-coordinates and a small dot may bestored in the print data memory 47 e. In this case, the combination ofthe other sub-coordinate and the small dot is not stored in the printdata memory 47 e.

(4) In the above embodiment, the PC 1 creates the print data. However,the print data creating device 70 (see FIG. 4) may equally well bemounted in the printer 2. In this case, the following variants arepossible.

For example, the printer 2 may equally well have a scanner function andbe capable of printing scanned images. In this case, the printer 2creates print data from the bit-mapped data obtained from the scannedimage, and executes the printing operation based on the print data thathas been created.

Further, the PC 1 may output the two value data obtained at step S26(see FIG. 8) to the printer 2. The printer 2 may create the print databased on the two value data output from the PC 1.

(5) A computing device other than the PC 1, such as a tablet, a PDA,etc. may be adopted as the print data creating device.

(6) As shown in FIG. 3, the PC 1 and the printer 2 are connected by acable 40. However, wireless communication may be utilized instead of thecable 40.

(7) The aforementioned printer 2 is a line type printer. However, thepresent technique may equally well be utilized in a serial type printerin which the ink jet heads move. The print data creating device 70 mayequally well create print data utilized by a serial type printer inwhich the ink jet heads move.

(8) The aforementioned coordinates need not be represented in the formof coordinates. For example, the coordinates can be represented by acombination of the nozzle number of the ink jet printer and the timingwith which the ink is discharged.

1. A method for manufacturing a computer program product utilized by acomputer device to create print data utilized by a printer, the printdata including a coordinate at which the printer tries to form a dot ona print medium, the method comprising: a forming step of instructing theprinter to form a dot at a predetermined coordinate; a combining step ofcreating a combination of the predetermined coordinate and asub-coordinate which is different from the predetermined coordinate,wherein the combining step is performed in a case where a distancebetween the predetermined coordinate and a position of the dot formed inthe forming step is more than a predetermined distance, and a distancebetween the predetermined coordinate and a position of a dot formed whenthe printer tries to form the dot at the sub-coordinate is shorter thanthe distance between the predetermined coordinate and the position ofthe dot formed in the forming step; and a storing step of storing acomputer program into a memory medium, wherein the computer programincludes instructions for ordering the computer device to perform: achoosing step of choosing a coordinate from bit-mapped data, thebit-mapped data including a plurality of combinations of a coordinateand color information, wherein the choosing step chooses the coordinatebased on the color information being combined with the coordinate; and aconverting step of converting the coordinate chosen in the choosing stepinto the sub-coordinate in a case where the coordinate chosen in thechoosing step has been combined with the sub-coordinate in the combiningstep.
 2. The method as in claim 1, wherein the computer device utilizesthe computer program product to create the print data utilized by an inkjet printer, the ink jet printer comprises a plurality of nozzles fordischarging ink toward the print medium and a transferring device fortransferring the nozzles and/or the print medium along a Y direction ina state in which at least one nozzle faces the print medium, each nozzleis offset along a X direction which is perpendicular to the Y direction,and each nozzle is capable of forming a plurality of dots aligned alongthe Y direction.
 3. The method as in claim 2, wherein the forming stepinstructs the ink jet printer to discharge ink from each nozzle to forma dot at a predetermined coordinate corresponding with each nozzle, thecombining step creates first combinations, each first combination is acombination of the nozzle and an adjustment amount, and the convertingstep converts the coordinate chosen in the choosing step into thesub-coordinate by (1) specifying the adjustment amount being combinedwith the nozzle for forming a dot at the coordinate chosen in thechoosing step, and (2) adding the specified adjustment amount to a Ycoordinate of the coordinate chosen in the choosing step.
 4. The methodas in claim 3, wherein the first combinations include secondcombinations and third combinations, each second combination is acombination of the nozzle and a difference amount between a Y coordinateof the predetermined coordinate corresponding with the nozzle and a Ycoordinate of the dot formed by the nozzle in the forming step, and eachthird combination is a combination of the difference amount and theadjustment amount.
 5. A device for creating print data utilized by aprinter, the print data including a coordinate at which the printertries to form a dot on a print medium, the print data creating devicecomprising: a storage for storing a combination of a predeterminedcoordinate and a sub-coordinate which is different from thepredetermined coordinate, wherein a distance between the predeterminedcoordinate and a position of a dot formed when the printer tries to formthe dot at the sub-coordinate is shorter than a distance between thepredetermined coordinate and a position of a dot formed when the printertries to form the dot at the predetermined coordinate; a choosing devicefor choosing a coordinate from bit-mapped data, the bit-mapped dataincluding a plurality of combinations of a coordinate and colorinformation, and the choosing device choosing the coordinate based onthe color information being combined with the coordinate; and aconverting device for converting the coordinate chosen by the choosingdevice into the sub-coordinate in a case where the coordinate chosen bythe choosing device has been combined with the sub-coordinate in thestorage.
 6. The print data creating device as in claim 5, wherein theprinter is an ink jet printer, the ink jet printer comprises a pluralityof nozzles for discharging ink toward the print medium and atransferring device for transferring the nozzles and/or the print mediumalong a Y direction in a state in which at least one nozzle faces theprint medium, and each nozzle is offset along a X direction which isperpendicular to the Y direction, and each nozzle is capable of forminga plurality of dots aligned along the Y direction.
 7. The print datacreating device as in claim 6, wherein the ink jet printer is a linetype ink jet printer.
 8. The print data creating device as in claim 6,wherein the storage stores first combinations, each first combination isa combination of the nozzle and an adjustment amount, the convertingdevice converts the coordinate chosen by the choosing device into thesub-coordinate by (1) specifying the adjustment amount being combinedwith the nozzle for forming a dot at the coordinate chosen by thechoosing device, and (2) adding the specified adjustment amount to a Ycoordinate of the coordinate chosen by the choosing device.
 9. The printdata creating device as in claim 8, wherein the first combinationsinclude second combinations and third combinations, each secondcombination is a combination of the nozzle and a difference amountbetween a Y coordinate of a predetermined coordinate corresponding withthe nozzle and a Y coordinate of a dot formed when the printer tries toform the dot at the predetermined coordinate corresponding with thenozzle, and each third combination is a combination of the differenceamount and the adjustment amount.
 10. The print data creating device asin claim 8, wherein the choosing device is capable of choosing aplurality of coordinates from the bit-mapped data, the converting deviceconverts the coordinate corresponding with the nozzle being combinedwith the adjustment amount into the sub-coordinate, the convertingdevice does not convert the coordinate corresponding with the nozzle notbeing combined with the adjustment amount, and the converting device iscapable of creating the print data which includes the sub-coordinate andthe unconverted coordinate.
 11. The print data creating device as inclaim 5, wherein the choosing device is capable of choosing a pluralityof coordinates from the bit-mapped data, the converting device convertsthe coordinate being combined with the sub-coordinate into thesub-coordinate, the converting device does not convert the coordinatenot being combined with the sub-coordinate, and the converting device iscapable of creating the print data which includes the sub-coordinate andthe unconverted coordinate.
 12. The print data creating device as inclaim 11, wherein the printer is an ink jet printer, the ink jet printercomprises a plurality of nozzles for discharging ink toward the printmedium, the ink jet printer is capable of changing a unit ink quantitywhich is an ink quantity discharged from one nozzle to form one dot onthe print medium, and the converting device is capable of creating printdata which includes a combination of the sub-coordinate and the unit inkquantity, and a combination of the unconverted coordinate and the unitink quantity.
 13. The print data creating device as in claim 12, whereinthe storage stores a combination of the predetermined coordinate and atleast two neighboring sub-coordinates, the converting device convertsthe coordinate being combined with the at least two neighboringsub-coordinates into the at least two neighboring sub-coordinates, eachof the at least two neighboring sub-coordinates is combined with a firstunit ink quantity, the unconverted coordinate is combined with a secondunit ink quantity, and the first unit ink quantity is smaller than thesecond unit ink quantity.
 14. The print data creating device as in claim5, wherein the print data creating device is configured separately fromthe printer, the print data creating device is capable of communicatingwith the printer, and the print data creating device outputs the printdata to the printer.
 15. A method for creating print data utilized by aprinter, the print data including a coordinate at which the printertries to form a dot on a print medium, the print data creating methodcomprising: a choosing step of choosing a coordinate from bit-mappeddata, the bit-mapped data including a plurality of combinations of acoordinate and color information, and the choosing step choosing thecoordinate based on the color information being combined with thecoordinate; and a converting step of converting the coordinate chosen inthe choosing step into a sub-coordinate, wherein a distance between thecoordinate chosen in the choosing step and a position of a dot formedwhen the printer tries to form the dot at the sub-coordinate is shorterthan a distance between the coordinate chosen in the choosing step and aposition of a dot formed when the printer tries to form the dot at thecoordinate chosen in the choosing step.
 16. A computer program productutilized by a computer device to create print data utilized by aprinter, the print data including a coordinate at which the printertries to form a dot on a print medium, wherein the computer programproduct stores a combination of a predetermined coordinate and asub-coordinate which is different from the predetermined coordinate, anda distance between the predetermined coordinate and a position of a dotformed when the printer tries to form the dot at the sub-coordinate isshorter than a distance between the predetermined coordinate and aposition of a dot formed when the printer tries to form the dot at thepredetermined coordinate, and the computer program product includesinstructions for ordering the computer device to perform: a choosingstep of choosing a coordinate from bit-mapped data, the bit-mapped dataincluding a plurality of combinations of a coordinate and colorinformation, and the choosing step chooses the coordinate based on thecolor information being combined with the coordinate; a converting stepof converting the coordinate chosen in the choosing step into thesub-coordinate in a case where the coordinate chosen in the choosingstep was combined with the sub-coordinate in the computer programproduct.